Power press cushion lubricating apparatus



Jan. 7 M58 11... s. PLATOU 2 1,611

POWER PRESS CUSHION LUBRICATING APPARATUS Filed March 30, 1955 v INVENTOR. LEA/S. pLA TOU @aaw, 1

,4 TTORA/EVS hired States POWER PRESS CUSHION LUBRICATING APPARATUS Leiv S. Platou, Buffalo, N. Y., assignor to Niagara Machine & Tool Works, Bufialo, N. Y.

This invention relates generally to sheet metal drawing presses and to similar power presses having yieldable pressure pads or cushion devices associated with the bed portions thereof.

The bed portions of power presses are frequently provided with yieldable resilient means, commonly referred to as pressure pads or cushions, such cushion means being most commonly employed for yieldably supporting draw rings which are associated with drawing dies, although they may be used for other purposes, as desired.

Power press cushions of this general type usually employ air under pressure as the yieldably resilient medium and such cushions commonly involve relatively large piston and cylinder members disposed within the bed portions of presses provided with the same. The nature of the construction is usually such as to render the cushion mechanism relatively inaccessible and accordingly a substantial problem is involved in maintaining proper lubrication of the reciprocating piston and cylinder parts of the cushion.

it has been proposed to provide lubricant fittings or conduits which lead outwardly from the piston and cylinder surfaces of the cushion means to some accessible point about the base of the power press, but such means require frequent attention and their mere presence gives no assurance that the concealed parts of the cushion are properly lubricated.

The present invention provides a power press cushion structure wherein means are provided for maintaining continuous and entirely adequate lubrication of the relatively intersliding piston and cylinder surfaces with relatively no attention and with no exposed or projecting lubricant fittings. Furthermore, the punch press cushion lubricating apparatus of the present invention is auto matic in its operation in that the reciprocating movements of the cushion produce a pumping action to deliver lubricant under pressure to the surfaces to be lubricated with simple and effective means for returning excess lubricant to a common supply point.

This arrangement not only makes it entirely unnecessary to gain access to the cushion apparatus for lubrication but insures proper lubrication without excess lubricant delivery since the delivery of lubricant under pressure is entirely proportionate to the degree of use to which the cushion is subjected. This proportionality of force feed lubrication extends not only to the frequency of use of the cushion but also to the amplitude of individual movements thereof. A stroke of the lubricant pump accompanies each stroke of the cushion means and the amplitude of each stroke of the lubricant pump is in proportion to the amplitude of movement of the cushion means.

Various mechanical modifications may be made in the apparatus set forth in the following specification and illustrated in the accompanying drawing without departing from the principles of the present invention. The apparatus set forth herein in detail is by way of example 2,3 l tlfilfi l Patented Jan. 7, 1958 i in only and the present invention is limited in scope only as defined in the appended claims.

The single figure of the drawing is a vertical crosssectional view through the bed portion of a power press provided with one form of the fluid pressure cushion means and lubricating arrangement of the present invention.

in the drawing the numeral 10 designates the usual bed of a power press and the numerals 11 and 12 designate front and rear structural members of the base portion of such a press. A conventional bolster plate 13 is disposed on bed 10 and an opening in the latter receives a pressure plate or pressure pad 14 of a power press cushion apparatus. The numeral 15 designates a number of draw pins which extend slidably through bolster '13 and bear against pressure plate 14. The latter is downwardly yieldable and the manner in which pressure plates and cushions are employed in sheet metal forming and drawing practice is conventional and well known.

In the drawing a rigid substructure is designated by the numeral '20 and is fixed to or forms a part of the rigid base or bed structure of the power press. An upwardly opening hollow casing member 21 is mounted upon and fixed to substructure Ztl, forming an oil sump or reservoir 22. An annular piston member 24 is fixed to the upper end of hollow casing member 21 and an elongated plunger 25 is fixed at its lower end in the lower end of casing member 21 and extends upwardly, axially with respect to annular piston member 24. The foregoing casing, piston and plunger structure is all relatively fixed and in the present instance comprises the fixed portion of the air cushion piston and cylinder structure.

A downwardly opening cylinder member 30 is fixed to the under side of pressure plate 14 and has a skirt portion which is slidable axially upon the exterior periphery of annular cylinder member 24. A piston member 32 is fixed at its upper end to the upper wall portion of cylinder member 3%) and extends downwardly within and in axial sliding relation with respect to the interior of annular piston member 24. A bore 33 extends upwardly from the lower end of piston member 32 and plunger 25 is vertically slidable therein upon relative movement between piston member 32 and the fixed structure which includes casing member 21. Bore 33 is closed at its upper end by a removable plug 34 and cylinder member 30 is provided with an opening 37 to give access to plug 34 for pre-filling the system, to avoid trapping air in the bores 33 and 35.

Plunger 25 is axially bored throughout its length as at 35 and the bore 35 communicates at its lower end with a conduit 36. It will therefore be seen that bore 33 and plunger 25 comprise a piston and cylinder pump for which conduit 36 serves as both the inlet and outlet passage.

The interior of cylinder member 39 and the interior portions of casing member 21 and annular piston mem ber 24 mutually form a pneumatic pressure chamber. Annular piston member 24 is provided with a plurality of vertical passages 38 which establish free fluid communication between the interior of cylinder member 30 and the interior of casing member 21 and the latter is provided with an air pressure conduit 39 for maintaining a predetermined degree of air pressure within casing member 21 and the interior of cylinder member 3t Conduit 39 leads from the source of air under substantial pressure, usually by way of a surge tank whereby a relatively constant pressure is maintained within casing member 21 and cylinder member 3%) despite changes in volume due to depression of cylinder member 35 Fluid conduit 36 terminates at one end in a passage 4-1 which connects conduit 36 with the oil reservoir'22. A one-way check valve 43 permits fiuid flow from reservoir 22 into conduit 36 but prevents retrograde flow while a check valve 44 permits free fluid flow from the lefthand end of conduit 36 but prevents retrograde flow. The end of conduit 36 which includes check valve 44 connects with a pressure passage 46 leading upwardly through the wall of easing member 21, thence horizontally by way of a passage 47, and again upwardly by way of a passage 48 extending upwardly in the wall of annular piston member 24.

At its upper end passage 48 has a radially outwardly extending portion 49 which leads into an annular well 50 formed at the upper end of annular piston. member 24 by means of an external annular recess at such upper end of the piston member. This external annular recess may further receive a U-shaped packing ring 52. In the illustrated instance the lateral passage portion 47 also connects with a conduit 54 leading to a pressure gauge 55.

Annular piston member 24 is provided with a lateral passage 60 which intersects vertical passage 48 and leads to a vertical passage 61 having an upper reduced vertical passage portion 62. Passage 61 communicates with internal annular grooves 64 and 65 formed in the interior periphery of annular piston member 24 and communicating with openings 67 in a bushing 68 which provides a bearing surface for slidably receiving piston member 32.

The upper restricted passage portion 62 terminates in an annular well formation 70 which is formed at the upper end of the interior periphery of annular piston member 24.

The foregoing passages supply fluid to the annular external and internal Well formations t? and 70, respectively, fluid being intermittently pumped thereto upon each working stroke of pressure pad 14 and cylinder member and in proportion to the amplitude of such stroke. Excess lubricant from the annular wells 50 and 70 drains downwardly into the space between the external and internal portions of annular piston member 24, thence through the vertical passages 38 and back to reservoir 22.

Each downward stroke of pressure pad 14 and cylinder member 30 reduces the volumetric capacity of bore 33 of piston member 32 and forces lubricant past check valve 44 and upwardly to the annular well formations 50 and 70 and radially inwardly through the bushing passages 67 to thoroughly lubricate all of the intersliding cylindrical surfaces of the piston and cylinder assembly. Each return stroke of pressure pad 14 again increases the capacity of bore 33 and during this stroke check valve 44 will be closed and oil will flow from reservoir 22 through passage 41, conduit 36, and bore of plunger 25 into bore 33.

There is no necessity for packing other than the U shaped packing ring 52 since all excess lubricant from the piston surface 32 and the bushing 68 drains back to reservoir 22, whether it finds egress at either the upper or lower end of bushing 68.

Reservoir 22 has a horizontal filler passage 74 and a lower horizontal drain passage 75. A vertical passage connects the horizontal passages 74 and 75 and lies behind force feed lubricant passage 46, out of the plane of the cross sectional view. This vertical passage extends downwardly out of casing 21 and terminates in a drain conduit 77. A filler conduit 78 connects with the upper horizontal filler passage 74.

The foregoing cushion lubricating arrangement is fully as effective whether the power press with which it is associated is used in the vertical position illustrated or in an inclined position such as is commonly employed in power presses.

What is claimed is:

1. In a power press, a bed structure and a pressure pad associated therewith, an annular piston fixed at its lower portion to said bed structure, said pressure pad including a depending cylindrical member extending slidably about said annular piston and a depending piston extending slidably into said annular piston, means for maintaining air pressure between said annular piston and said cylinder member to yieldably urge said pressure pad to raised position, oil pump means comprising an opening in said depending piston and a plunger fixed with respect to said bed structure and extending upwardly for sliding engagement in said opening, and oil pressure passage means for conducting oil under pressure from the oil pump means to the interior and exterior peripheries of said annular piston.

2. In a power press, a bed structure and a pressure pad associated therewith, an annular piston fixed-at its lower portion to said bed structure, said pressure pad including a depending cylindrical member extending slidably about said annular piston and a depending piston extending slidably into said annular piston, means for maintaining air pressure between said annular piston and said cylinder member to yieldably urge said pressure pad to raised position, oil pump means comprising an opening in said depending pressure pad piston and a plunger fixed with respect to said bed structure and extending upwardly for sliding engagement in said opening and oil pressure passage means extending downwardly through said plunger and upwardly in said annular piston for conducting oil under pressure from the oil pump means to the interior and exterior peripheries of said annular piston.

3. In a power press, a bed structure and a pressure pad associated therewith, an annular piston fixed at its lower portion to said bed structure, an oil reservoir beneath said annular piston, said pressure pad including a depending cylindrical member extending slidably about said annular piston and a depending piston extending slidably into said annular piston, means for maintaining air pressure between said annular piston and said cylinder member to yieldably urge said pressure pad to raised position, oil pump means comprising an opening in said depending pressure pad piston and a plunger fixed with respect to said bed structure and extending upwardly for sliding engagement in said opening, and oil pressure passage means from said reservoir to the oil pump means and from the latter to the interior and exterior peripheries of said annular piston.

4. in a power press, a bed structure and a pressure pad associated therewith, an annular piston fixed at its lower portion to said bed structure, an oil reservoir beneath said annular piston, said pressure pad including a de pending cylindrical member extending slidably about said annular piston and a depending piston extending slidably into said annular piston, means for maintaining air pressure between said annular piston and said cylinder member to yieldably urge said pressure pad to raised position, oil pump means comprising an opening in said depending pressure pad piston and a plunger fixed with respect to said bed structure and extending upwardly for sliding engagement in said opening, oil pressure passage means from said reservoir to the oil pump means and from the latter to the interior and exterior peripheries of said annular piston, and drain passage means in said annular piston to return excess oil from said piston peripheries to said reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 1,198,643 Liebau Sept. 19, 1916 1,437,894 Holmes Dec. 5, 1922 1,454,905 Poindexter May 15, 1923 2,403,339 Byerlein July 2, 1946 2,665,901 Patterson Jan. 12, 1.954 

